Forensic police were still trying to find the cause of the fire that gutted part of Soneva Kiri Koh Kood, a luxury resort on Koh Kut in Trat province on Sunday, Pol Lt Gen Sompong Chingduang, the assistant national police chief, said on Thursday.
He said an initial investigation indicated the fire may have started in one of the rooms in the resort's main building.
Since all the buildings were made of wood, possible factors including a discarded cigarette or a short circuit have yet to be eliminated.
Pol Lt Gen Sompong said police will question remaining witnesses including the hotel owner and guests, after finishing with 17 other witnesses.
They include eight guests, six ordinary staff members and a general manager, as well as a security guard and an electrician.
Additionally, investigators were looking closely at why the resort's alarm and fire sprinkler systems failed, as well as related documents about the hotel licence, security protocols and financial records dating back over the past three years.
A media report said the installation of an additional spotlight around the pool may have caused the blaze.
Meanwhile, Suthipol Thaweechaikarn, secretary-general of the Office of Insurance Commission (OIC), said the resort took out fire insurance with five firms supporting the underwriting led by Krungthai Panich Insurance.
The resort also took out third-party insurance with AIG Insurance (Thailand) with a ceiling limit of 330 million baht, he said.